Fish care

Watching your fish swim around is one of the rewarding perks of aquaponics. Being able to see your fish is also one of the easiest ways to check they’re healthy.

As soon as you own fish, you quickly learn what their behaviour indicates. Happy fish play in their tank more, which is more interesting to watch, and they are generally healthier. We recommend that your aquaponics system has a good view into the aquaculture section.

All aquaculture are highly dependent on the water in which they live, so changes within the water will have a direct impact on their health and well-being. Often these changes are invisible to the naked eye, so as well as monitoring their behaviour and colour, it is also important to test their water regularly.

Behaviour: unusual swimming patterns – darting around the tank in alarmed fashion, rubbing against objects in the tank, unusual positioning – hanging at the surface, hiding away and being unusually shy

COMMON MISTAKES

Cleaning the filter foams with tap water: tap water contains chlorine and chloramine that will kill the beneficial bacteria that live in the filter. This will result in a build up of ammonia and nitrite. Filter foams should be rinsed in a jug of water from the aquarium they came from.

Over-feeding: Fish should be fed no more than 2-3 times a day, and given no more than they can consume within 5 minutes. Any excess food should be removed from the tank with a net, as excessive levels of solid waste will lead to deteriorating water quality, and provide better conditions for disease-causing organisms.

Over-stocking: If you have too many fish in one tank, it will become more difficult to maintain good water quality. Air pumps can be added to help increase oxygen levels, but physical damage and stress are more common in over-stocked tanks.

Dirty gravel: Before placing gravel in the tank it should be boiled to make sure it is free from disease. If it is allowed to get dirty in the aquarium it can provide a good environment for disease-causing organisms, and may cause increased pollutants, and decreased oxygen.

Incompatibility: Make sure all your inhabitants are compatible before you buy them. If you already have an aggressive fish, you may have to re-home it. Just like in a playground, problems often occur due to one particular fish bullying or being aggressive towards others. This can cause your fish health problems.

Use of heavy metal or copper pipes: Fish can be killed by metals, so don’t be tempted to use metal fixings or copper pipes if you’re building your own aquaponics system.

Damaging décor: Sharp objects in a tank can damage the fish. This often happens when fish are startled and dart away. Physical damage caused this way can quickly lead to infection. It is safest to remove these items from the aquarium.

WHAT CAUSES FISH DISEASE?

Like all animals, fish carry their own population of miniature life forms such as bacteria, virus, fungus and parasites which exist by living in or on the fish. Not all of these are undesirable, but some of these micro-organisms have potential to cause disease, and are called pathogens.

Like us, fish rely on their immune system to create barriers to prevent the diseases. There is a delicate balance in aquariums to make sure the fish remain healthy. So not so surprisingly, things such as stress can upset this balanceand allow them to get ill.

The following factors can all cause stress (You might be able to relate to these too)

Poor water quality/environment

Not getting along with other fish

Incorrect/poor Diet

Capture or movement

Insufficient hiding places

Diseases can also be introduced by new fish, plants, invertebrates, live food, aquarium decorations or equipment such as nets.

PREVENTING DISEASES

Prevention is better than a cure. Before introducing new fish into an established aquarium you should quarantine them in a separate aquarium for two weeks with the same pH and hardness as the eventual system.

Feeding them a good, varied and well balanced diet

Maintaining stable water quality – through temperature control and water testing kits you can monitor the correct environment for your type of fish. Regular water changes will help maintain the water quality.

Create ideal habitat – give them hiding places, and try and make your tank as natural for them as possible

Adding aquarium salts: these salts help safeguard against diseases such as ulcers, dropsy and fungus. They stabilise the water and act as a pH buffer. They help the fish maintain a constant internal body environment and help reduce the toxic effects of waste products such as nitrite.

Good hygiene/biosecurity – using clean equipment such as nets, pots etc. This will lower the risk of both fish and plant diseases.

STOCKING DENSITY

We are humane fish keepers. We keep quite low stocking densities, to keep the fish happy but we also need a certain amount of waste to be produced to feed the plants.

Stocking Density can be calculated by the weight of the fish to volume of water (including grow-bed) as opposed to number of fish to volume of water. This also helps us calculate how much fresh veg to plant – as every kg of fish equates to around 30-50 kg of fresh produce.

Factors such as feed rate, water flow, oxygen levels, plants, pump rates, fish species will all impact stocking density.

The rule of thumb is often 1 fish per 5-10gal of water or 1cm of fish per litre. Building up your stock slowly is advised, as it allows your system time to mature to it’s optimum.

Don’t overstock them. Stocking too many fish can lead to problems such as;

FISH FOOD

One of the most essential elements, as it controls the fish and overall biological filter. It can also provide plants with some of the nutrients they need.

Different fish have different diets:

Some fish are herbivores such as plecos, and African cichlids who will eat algae as well as root mass from harvested vegetables.

Most fish are omnivores and require both animal and plant produce these fish include goldfish and catfish. We feed our Koi and goldfish spoils from the grow-bed such as beetroot leaves/roots or marigold petals. We find it greatly enhances their colour!

A few species are carnivores and only eat meat, such as bettas or oscars which will eat worms – which also make a great addition to the grow-bed, or insects – insects are high in protein and you can easily grow insects at home! Tip: 1/2 of what carnivorous fish eat needs to be protein. Also see our section on cycling for tips on cycling with carnivorous fish.

All fish eat different amounts. A rule of thumb when choosing portion size is all they can eat hungrily within 5 minutes. Remove any excess, as this could lead to a spike in ammonia.

COMMERCIAL FEEDS

Many off the shelf feeds are available for the home aquarium and commercial aquaculture. However, many are unsuitable for aquaponics. Some of the feeds used in aquaculture have been developed to reduce nitrate output into our waterways from fisheries, whilst in aquaponics we make use of those nitrates.

We are developing a range of feeds specifically for use in aquaponics, which is balanced for the fish and plants whilst coming from a sustainable, organic source.

One of the least attractive things about keeping pets is how unsustainable their food is, and it’s no different with keeping fish; A high percentage of fish foods contain fish and shrimp meal which is caught by destroying our oceans.

The fish food we use is of sustainable origin. Unfortunately however, the vast majority of feeds currently produced are unsustainable, meaning it would take a greater mass of fish from the sea to grow the fish in your tank.

1kg farmed fish you buy from a supermarket has eaten up to 2kg of fish sourced from our oceans (often krill)

To tackle this truly devastating problem we can make our own fish food. It may seem more time consuming, but it greatly outweighs the alternative option, which ruins marine life.

HOME MADE FEEDS

For species such as Tilapia sustainable feeds are easy to come by, the simplest of which is home grown algae and duck weed, they will also live quite happily on the produce scraps. Trout on the other hand require a high protein diet which can be catered for by breeding black soldier fly larvae, insects, worms and using hemp seed.

It is important to feed your fish the right food, not just for their health, but for yours too if you are going to eat them. With any animal, you will eat what they eat, and this will dictate the way they taste. Unlike fishing, no-one ever complains aquaponic fish taste ‘muddy’.

Tip: Grow marigolds not only to repel greenfly, but because their petals can be added into your fish food as a natural colour enhancer for your fish. When growing beetroot, you can give some to Goldfish or Koi as this is another way to naturally enhance their colour.